In recent years, innovation in the area of silicon integrated circuits has proved to be a major factor in the growth of the electronics industry. Current devices are of a scale on the order of tenths of micrometers. One goal of circuit designers is to further reduce the size of the chip space required for circuit components. Reducing the utilized chip space may reduce the amount of power required to operate the chip, may reduce the temperature of the circuit, and may allow the circuit to operate faster and more efficiently. Some solutions have been proposed to create silicon integrated circuits on the nanometer scale, but they all have limitations.
An extension of silicon processing has enabled microelectromechanical systems (MEMS) development. By incorporating deposition, etch and photo lithography processing, micron scale mechanical structures can be combined with electronic devices.
On the nanometer scale, there is much interest in creating structures to enable chemical and biological sensors, nanoelectronics and photonic devices. Some approaches to constructing nanometer scale structures include fine scale lithography, nanoimprint lithography, direct writing of device components, and the direct chemical synthesis and linking of components with covalent bonds. Each of these conventional approaches has their own drawbacks.
Fine scale lithography utilizes X-rays, electrons, ions, scanning probes, or stamping to define device components on a silicon integrated circuit. Device alignment is a major problem with fine scale lithography. The wafer on which the devices are built must be aligned to within a fraction of a nanometer in two or more dimensions. This level of control is extremely expensive to implement. E-beam lithography, a type of fine scale lithography, is capable of producing lines on small scale, but is limited in the size and range over which the lines can be written. The E-beam lithographic method also requires a high vacuum, which precludes the use of most organic materials in producing nanoscaled components. Additionally, E-beam lithography is slow and expensive, making it commercially impractical.
Another conventional method for producing lines is Nano Imprint Lithography (“NIL”). This method requires the use of molds. These molds are typically created by E-beam lithographic methods and require high pressure. Limitations exist with respect to mold release and defect replication.
The direct writing of the device components by electrons, ions, or scanning probes also has drawbacks. This is a serial process. Therefore, the direct writing of a wafer full of complex devices, each containing trillions of components, requires an extraordinary amount of time. This makes direct writing impractical to implement in large-scale commercial applications.
Another method is direct chemical synthesis and linking of components with covalent bonds. The problem with this method is that the only known chemical analogues of high information content circuits used have been proteins and DNA. Both of these chemical analogues have extremely complex and, to date, unpredictable secondary and tertiary structures that cause them to twist into helices, fold into sheets, and form other complex three-dimensional structures. The resulting topography is not useful for making nanoscale structures.
Therefore, a need exists for a method and system that can create well ordered nanoscale structures using commercially feasible processes.